Aeronautics and astronautics – Aircraft – lighter-than-air – Airships
Reexamination Certificate
1999-11-01
2001-09-11
Jordan, Charles T. (Department: 3641)
Aeronautics and astronautics
Aircraft, lighter-than-air
Airships
C244S026000, C244S056000, C244S066000
Reexamination Certificate
active
06286783
ABSTRACT:
The invention relates to an aircraft with a fuselage designed essentially as an aerostatic lift body and with combined lift and propulsion devices, which are articulated on the fuselage. These combined propulsion and lift devices are provided with propellers and form propulsion units, which in each case tilt between a lift position and a propulsion position. In the lift position the respective propeller rotation plane is essentially horizontal and the output shaft of the associated drive is essentially vertical. In the propulsion position, the respective propeller rotation plane is essentially vertical and the output shaft of the associated drive is essentially horizontal.
CROSS-REFERENCES TO RELATED APPLICATIONS
Applicant claims foreign priority from WO 98/29303 published Jul. 9, 1998 filed from German DE 19700182.3 filed Jan. 4, 1997.
BACKGROUND OF THE INVENTION
Aerostatic aircraft provided with translation propulsion systems have long been known, for example, as Zeppelins. These airships can take off and land essentially vertically by virtue of their aerostatic lift behavior, but, since they are predominantly lighter than air, they have to be restrained whenever they are held on the ground. Moreover, these aircraft are relatively sluggish to control, since, because of their slow speed and their small aerodynamic control surfaces, they have low control authority, that is to say high reaction inertia to control movements. Admittedly, airships have recently become known, which have main propulsion systems that tilt comparatively slowly about a transverse axis and laterally act as auxiliary propulsion systems for assisting the aerodynamic control. These propulsion systems reduce the turning circle of an airship, but it has not been possible for the airship to achieve “pinpoint” maneuverability. Another disadvantage of airships with an elongated streamlined body shape is their extremely high sensitivity to crosswind. In cross-winds it is necessary to restrain the airship on the ground in such a way that it can turn into the wind in the same way as a boat at a buoy. Anchor masts generally being necessary for this purpose.
Furthermore, vertical take-off aircraft are known, the engines of which are tilt out of a vertical lift position with a horizontal propeller rotation plane and a horizontal propulsion position with a vertical propeller rotation plane. One problem of these vertical take-off aircraft with tilting engines is the control of the gyroscopic forces which occur when the engines are tilted and which have to be supported via solid supporting structures on the aircraft wings and on the fuselage. On account of these gyroscopic forces, the tilting of the engines can take place only relatively slowly. These vertical take-off aircraft are likewise controlled essentially via aerodynamic control devices. Since, during the vertical take-off of these aircraft, the engines alone have to generate the lift of the aircraft as a whole, the load capable of being transported in addition to the aircraft's own weight is very limited.
SUMMARY OF THE INVENTION
The object of the present invention, therefore, is to provide a generic aircraft which combines the advantages of an aerostatic aircraft and the advantages of a vertical takeoff aircraft and which is therefore capable of transporting large loads over relatively long ranges. The aircraft can land, quickly and accurately, without a special infrastructure on the ground being required for this purpose.
This object is achieved in that the respective propeller rotation plane has all-around inclination relative to the output shaft of the associated drive, this output shaft acting on the propeller shaft.
This inclination of the propeller rotation plane, in addition to the fundamentally provided tilt of the propulsion system about a transverse axis, allows thrust vector control of the aircraft. This thrust vector control reacts quickly and giving the aircraft a very agile control behavior even during take-off and landing. This thrust vector control makes it possible (assuming sufficient propulsion system power) to land the aircraft provided with the aerostatic lift body with essentially pinpoint accuracy. This affords the advantage that the aircraft can descend directly on relatively small outside landing areas and can thus, for example, pick up a load in a factory yard and deposit it again directly with the recipient.
The inclination of the rotor plane takes place due to aerodynamic forces acting on the propeller blades, as the result of individual adjustment of the respective angle of incidence of the individual propeller blades. In this case, only the thrust vector for propulsion, lift, and control is introduced as a force into the fuselage. Reaction moments occurring during a rapid build-up of the thrust vector, for example gyroscopic moments of an associated engine or of the propeller, are supported on the surrounding air and not on the structure of the aircraft. In this way, the propeller plane also tilts relative to the output shaft very quickly in any direction over a large angular sector, without reaction forces which in this case originate from gyroscopic moments having to be transmitted to the fuselage. The angle of inclination of the propeller rotation plane relative to the output shaft of the associated drive, said output shaft acting on the propeller shaft, may amount to between ±20° and ±50°, preferably between ±25° and ±35° and, for further preference, ±30°. Since the thrust vector control of the aircraft according to the invention works both in the propulsion position and in the lift position of the propulsion units, complicated restraint of the aircraft on the ground is not necessary for short landing stops. With the propulsion systems still running, the rapidly reacting thrust vector control allows stabilization of the position of the aircraft on the landing area, even in the event of crosswind or gusts of wind. As a result, the aircraft according to the invention becomes independent of landing platforms or other landing equipment provided on the ground, such as, for example, anchors for securing restraining lines for the aircraft. It may nevertheless be necessary, particularly when the aircraft stops for longer periods during which the engines are switched off, to restrain the aircraft on the ground in the known way. This may be carried out by anchoring a landing foot preferably integrated on the underside of the aircraft, or by means of a rope winch system, which is integrated into the fuselage and which can be activated preferably centrally. The rapid-reaction thrust vector control of the aircraft according to the invention also makes it possible to pick up a load, and deposit it with pinpoint accuracy, from the hovering state of the aircraft, without the latter itself having to land.
In a particularly preferred embodiment of the aircraft according to the invention, the fuselage is designed at the same time as an aerodynamic lift body. As a result, during cruising, the fuselage can also generate an aerodynamic lift force in addition to the aerostatic lift.
In the aircraft according to the invention, actively actuated aerodynamic control devices dependent on the dynamic pressure in flight may be dispensed with. There is no need to provide any horizontal elevator or rudder units which would increase the crosswind sensitivity and gust sensitivity of the aircraft, even though they do not essentially cooperate in controlling the aircraft in flight at low speed in the take-off phase and the landing phase. For this reason, this control is performed solely by the thrust vector control. The aircraft may thereby be designed with a consistently simple shape.
If the fuselage has an essentially circular plan and because of the larger volume a substantially increased lift is achieved. This is to be compared with the cigar-like shape of an airship of conventional type, assuming the same length. This leads directly to a higher payload. Assuming the same volume as a cigar-like shape of an airship, t
Best Christian M.
Jordan Charles T.
Townsend and Townsend / and Crew LLP
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